In some parts of the world that lack gas pipelines, fuel such as natural gas can be delivered in high pressure storage tanks on trucks, such as illustrated in FIG. 1. To maximize the capacity of a truck trailer, several large capacity tanks are combined with several smaller capacity tanks in an assembly. A manifold system is used to pressurize and depressurize all of these connected tanks via a common filling hose.
The connections between the tanks are designed so that in the event of a fire, the pressure in the tanks will be purged out of the tanks and into the atmosphere. In a known purging process, there is a possibility that a larger tank will backfill into a smaller tank instead of purging out to the atmosphere. To avoid this outcome, in the current state of the art, a pneumatic actuator is used in some systems, so that when the pressure in the system decreases, the actuator closes a valve to isolate the larger tanks from the smaller tanks. However, commonly used pneumatic actuators are not rated for the high pressures of the storage tanks; therefore, regulators must also be included in the system. The combination of the pneumatic actuators and the pressure regulators adds complexity and expense to the currently known systems.